1) Field of the Invention
The invention relates to the detection of fuel level variations in gas tanks. More particularly, the invention relates to activating a subsystem in response to the detection of a fuel level variation in a marine vehicle, like activating an indicator or a blower.
2) Description of the Prior Art
The fueling of marine vehicles usually generates a certain quantity of fumes which passengers may find disturbing. Fumes may also be dangerous in the advent of a spark which may occur during the operation of starting the marine vehicle motor. As a matter of fact, the American Boat & Yacht Council (ABYC) recommends running a blower for a period of four minutes prior to ignition, as per the US Code of Federal Regulations (CFR) (see the ABYC “Standards and Technical Information Reports for Small Crafts”, sections H-2.5.5 and H-2.6.3, and the Code of Federal Regulations at CFR 183.610(f), last updated in 2000). Even though fumes may be present at any time, they are particularly abundant during the refueling operation.
To counter this problem, several systems have been proposed, such as using an air pressure sensor to detect the correct functioning of an engine compartment fan, the ignition being disabled for a predetermined delay during which proper ventilation occurs; using a pressure sensitive switch to activate and deactivate the bilge blower in two steps: when the marine vehicle is stopped or moving slowly, water flowing in the switch activates the blower, whereas when the marine vehicle increases its speed, it begins skimming at the surface of the water resulting in the water flowing out of the switch and deactivating the blower; using a speed sensor to stop ventilation when the vehicle speed reaches a predetermined speed; using a vapor detector signal either as a vapor indicator, an ignition disabling trigger, or a blower actuator; and using a circuitry in the gas tank cap which activates a blower when the cap is removed and deactivates the blower then the cap is replaced.
These systems all present different means to increase boating safety by offering different types of triggers for a blower, adapted to different situations.